Multiple choice

Suppose the quadratic function $f\left( x \right) =a{ x }^{ 2 }+bx+c$ is such that $f\left( -2 \right) =0\quad and\quad \frac { -b }{ 2a } =1$, solve $f\left( x \right)=0$.

  1. $x=-2, 4$
  2. $x=2,-4$
  3. $x=2,6$
  4. $x=-2,-4$
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A Correct answer
Explanation

The vertex of the parabola is at x = -b/(2a) = 1. Since f(-2) = 0 and the axis of symmetry is x = 1, the other root must be equidistant from 1. The distance from -2 to 1 is 3, so the other root is 1 + 3 = 4.

AI explanation

The equation f(-2) = 0 means x = -2 is one root of the quadratic. The expression -b/2a = 1 represents the axis of symmetry, meaning the midpoint of the roots is 1. If one root is -2, the other root must be positioned symmetrically across 1, calculated as 2*1 - (-2) = 4. Thus, the solutions to f(x) = 0 are x = -2 and x = 4.